Combined spark plug and oscillatory circuit



Feb. 18, 1947.

E. K. VON MERTENS COMBINED SPARK PLUG AND OSCILLATORY CIRCUIT Filed April 24, 1945 INVENTOR,

Patented Feb. 18, 1947 1.1;; 2,415,979

UNITED STATES "PATENT-1* OFFICE Y COMBINED SPARK PLUG AND OSCILLATORY CIRCUIT Ernest K. Von Mertens, West Hartford, Conn., assignor to United Aircraft Corporation, East 7 Hartford, Conn, a corporation of Delaware Application Apr. 24, 1945, Serial No. 589,986

2 Claims. (01. 315-35) l 2 This invention relates to spark plugs for high Fig. 4 is a transverse sectional View, taken on frequency ignition systems of internal combusline 4-4 of Fig. 1, through the primary and section engines and it has for its object to improve ondary windings of the high frequency inducvthe construction and operating characteristics tion coil; and

of such devices.

- Fig. is a similar view taken on line 5-5 of Another object of the invention is to provide Fig. 1, through the coaxial electrodes of the spark a novel and improved spark plug having all the plug. d

elements of a high frequency oscillatory circuit. In the following description certain specific Another object is to simplify the construction terms are used for convenience in referring to and increase the operating efficiency of a spark the various details of the invention. These terms,

plug of the above type so that it may be made however, are to'be-interpretedas broadly as the of smaller and lighter parts than heretofore and state of the art will permit.

will enable a complete high frequency circuit to The spark plug shown in the drawing combe contained within a plug of approximately prises an outer shellor jacket ID of aluminum or the same size as the conventional spark plugs other suitable conducting material having a now in use. j spline-type wrench grip l2and'a threaded end Various other objects and advantages will be I [3 of standard design; v apparent as the nature of the invention is more Mounted in axial alignment Within the. shell fully disclosed. in are all the elements of a high frequencyoscile Spark p ug of the present invention conlatory circuit, consisting of a dischargecondenser tains all the elements of a high frequency oscil- I4 having its alternate plates grounded to the latory circuit, viz. a discharge condenser, a sealed shell III, a sealed spark gap comprising terminals Spark p a a high frequency i uct n coil, [5 and I6 sealed in an insulating housing I1, and arranged in a small compact unit. a high frequency induction coil comprising a According to a feature of the invention, the primary winding l8 and a secondary winding l9, c n a y Wi ding of the high frequ n y in insulated from each other by insulating sleeve tion coil is ungrounded or is left electrically floating. According to another feature, the elec- Withi th sh ll In of the spark plug is a tatrodes f th plu are arranged coaxiaily in Such pered hollow sleeve 20 of ceramic or other insua manner that the sp rki end of the elec-' so lating material; and mounted axially within said trodes coincides with an electrical reflection point sleeve 23 is t 2| of similar insulating of the oscillatory circuit. These structural featerjal through th center of which extends the tures, and others hereinafter described, increase t l l ctr de 23 of th spark plug, and upon the eificiency 0f the ys and enable the p the outer cylindrical surface of which is mounted to be made of smaller and lighte p with 5 the outer tubular tapered electrode 24 of the spark the r ult ha a mp hi fr qu n y ilplug. The coaxial electrodes 23 and 24 ma be .15 3 u t can be housed Within a pa p made of any suitable material such as a platiic is o larger than a p of co e o hum-tungsten alloy and they are preferably fired design. into union with the ceramic tube 2| which is Al ou the novel features which are charthen seated within the insulating sleeve 20 by a acteristic of this invention are set forth more taper a shown in Fig. 1.

in deta i t Claims pp hereto, the Haw Attached to the inner end of the ceramic tube tu and scope o e invention m y e better 2| is a concentric cylindrical portion 26 upon the understood y referring t the following de c pouter surface of which is wound the primary tion, taken in connection with the accompanywinding la of the high frequency induction coil, i e rawin formin a part thereof, in which a while between said cylindrical portion 26 and specific embodiment has b t forth o purtube 2| is wound the secondary Winding IQ of said poses of illustration. coil.

In the drawing: One end of the primary winding l8 of the in- Figure 1 isalongitudinal sectional view through so duction coil is connected to the terminal [6 of a spark plug embodying the invention; the spark gap, while the other end of said pri- Fig. 2 is a transverse sectional view through mary winding is grounded through conductor 21 the condenser, taken on line 2-2 of Fig. 1; to the outer shell ll] of the spark plug.

Fig. 8 is a similar view through the sealed spark One end of the secondary winding IQ of the gap, taken on line 3-3 of Fig. 1; 66 induction coil is connected at 28 to the central 3 electrode 23 of the spark plug, while the other end of said secondary winding is connected at 29 to the outer tubular electrode 24 of the spark plug. Thus the secondary winding of the induction coil is left electrically floating. Due to the foregoing construction,. furthermore, it will be noted that the arrangement of the electrodes is coaxial and that the sparking end of the electrodes 23 and 24 therefore coincides with an electrical reflection point of the oscillatory circuit.

The terminal wire 3| of the discharge condenser M, which is connected to the alternate ungrounded condenser plates and to the terminal I15 of the sealed spark gap, extends through a capping disk 32 which seats in a-circular ledge 33 in the upper end of the outer shell ID of the spark plug, and seals the assembly airtight as shown in Fig, 1. 7

Although a specific embodiment has been shown and descr'bed herein for purposes of illustration,

it, will be evident to those skilled in the art that invention is capable of various modifications and adaptations within the scope of the appended claims.

1i ,wWhatis claimed is:

1. A spark plug for high frequency ignition systerns comprising an outer shell of conducting material; a high frequency oscillatory circuit including a discharge condenser, a sealed spark gap and a high frequency inductionjcoil all housed in said shell, a pair of coaxial sparking electrodes including a central electrode and an outer tu- ..bular' electrode mounted in said shell and being uniformly spaced from one another throughout theirllerigths', saidcondenserhavin'g a terminal "conductor connected. to one'terminal of said spark gap, said induction coil including a primary winding having one end connected to the second terininal of said spark gap and the other end grounded to saidishell, and a secondarywinding having Number one end connected to said central sparking neetrode and the other end connected to said outer tubular electrode.

2. A spark plug for high frequency ignition systems comprising an outer shell of conducting material, a high frequency oscillatory circuit including a discharge condenser, a sealed spark gap and a high frequency induction coil all mounted in axial alignment within said shell, 2. pair of substantially equally spaced coaxial sparking electrodes including ace'ntral electrode and an outer tubular electrode mounted in said shell in axial alignment with the aforesaid elements of the oscillatory circuit and being uniformly spaced from one another throughout their lengths, said condenser including a plurality of spaced condenser plates grounded to said shell and a terminal conductor connecting a plurality of alternate ungrounded plates to one terminal of said spark gap, said induction coil including a primary winding having one end connected to the second terminal of said spark gap and the other end grounded to said shell, and an ungrounded secondary winding having one end connected to said central sparking electrode and the other end connected to said outer tubular electrode.

ERNEST K. VON MERTENS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 1,393,866 Whisler Oct. 18, 1921 1,395,375 Whisler Nov. 1, 1921 2,378,893 Berkey June 26, 1945 2,093,484 Randolph Sept. 21, 193? 2,347,286 Sandretto Apr. 25, 1944 2,372,429 Jones Mar. 27, 1945 

